Even when compared to coal, nuclear power fails the test if investments are made to increase the efficient use of the existing energy supply. One recent study by the Rocky Mountain Institute found that "even under the most optimistic cost projections for future nuclear electricity, efficiency is found to be 2.5 to 10 times more cost effective for CO2-abatement. Thus, to the extent that investments in nuclear power divert funds away from efficiency, the pursuit of a nuclear response to global warming would effectively exacerbate the problem."